大气等离子喷涂NiCr/Cr3C2复合涂层的性能

Properties of atmospheric plasma-sprayed NiCr/Cr3C2 composite coating

采用化工冶金包覆、固相合金化和喷雾造粒技术制备了NiCr/Cr3C2复合粉体,并采用大气等离子喷涂技术制备了NiCr/Cr3C2复合涂层,采用SEM、显微硬度计、万能试验机和马弗炉对粉体和涂层的显微结构、涂层的显微硬度、结合强度和氧化性能进行了分析。结果显示:NiCr/Cr3C2涂层呈典型的层状结构,各层间结合良好,结合强度为(27.4±5)MPa,涂层显微硬度约850HV0.2,为结合层显微硬度的2.7倍,涂层为典型的脆性断裂,断裂的位置发生在涂层的层与层之间。NiCr/Cr3C2涂层850℃氧化动力学曲线基本符合抛物线氧化规律。在氧化过程中涂层表面生产了氧化膜,且氧化膜会发生脱落,同时涂层内部出现了偏析现象,析出了金属Cr。

NiCr/Cr3C2 composite powder was prepared by chemical and metallurgical coating,solid state alloying and spray granulation technology,and the NiCr/Cr3C2 composite coating was prepared by atmospheric plasma spraying technology(APS).The microstructure of both the powder and the coating,as well as the microhardness,tensile strength and oxidation property of the coating were studied by using SEM,microhardness tester,universal mechanical tester and muffle furnace.The results show that the coating has a typical layered structure with excellent tensile strength(27.4±5)MPa.The microhardness of the coating is about 850HV0.2,which is 2.7 times of that of bonding layer.The fracture of the coating is a typical brittle fracture,and occurs between the layers in the coating.The oxidation kinetics curve of the coating at 850℃basically conforms to the parabola law,and the oxide film is produced on the surface of the coating,and will fall off during the oxidation process.At the same time,the segregation phenomenon appears in the coating,and the metal Cr is precipitated.